ld/NEWS

   1 -*- text -*-
   2
   3 * New ELF --add-needed/--no-add-needed options to control if a
   4 DT_NEEDED tag should be added when a shared library comes from
   5 DT_NEEDED tags.
   6
   7 * Support for the crx-elf target added.
   8
   9 * Support for the sh-symbianelf target added.
  10
  11 * A new linker command line switch has been added which allows the hash table
  12   size to be set to a suitable prime value near to its argument.  This switch
  13   is --hash-size=<NUMBER>.  Also if the switch --reduce-memory-overheads is
  14   used, and --hash-size has not been used, then the default value will be set
  15   to 1021.
  16
  17 * Linker map files are now generated with an O(N) algorithm for finding symbols
  18   that are defined in each section.  This uses about 40% more memory for
  19   symbols than the old O(N^2) algorithm.  You can use the new
  20   --reduce-memory-overheads option to select the old algorithm; this option
  21   might also be used in the future to select similar tradeoffs.
  22
  23 Changes in 2.15:
  24
  25 * New ELF --as-needed/--no-as-needed options to control if a DT_NEEDED
  26 tag should be added only when a shared library is referenced.
  27
  28 * New PE --large-address-aware option to indicate executables support virtual
  29   addresses greater than 2 gigabytes.
  30
  31 * DWARF 2 support for i386pe added.
  32
  33 * The linker script operator DEFINED() will now yield 1 only for a symbol that
  34   is defined before the statement where DEFINED is used.
  35
  36 * The MIPS --embedded-relocs (used to embed relocations into binaries for
  37   Embedded-PIC code) is deprecated and will be removed in a future release.
  38
  39 * cr16c support added by NSC.
  40
  41 * m32r Linux (ELF) support added by Renesas.
  42
  43 * Improved linker's handling of unresolved symbols.  The switch
  44   --unresolved-symbols=<method> has been added to tell the linker when it
  45   should report them and the switch --warn-unresolved-symbols has been added to
  46   make reports be issued as warning messages rather than errors.
  47
  48 Changes in 2.14:
  49
  50 * Added support for Xtensa architecture.
  51
  52 * Added --with-sysroot configure switch to specify a target system root, for
  53   linking against a target filesystem image.
  54
  55 * Added --accept-unknown-linker-format to restore old linker behaviour (pre
  56   2.14) of silently accepting and linking in any files in an unknown binary
  57   file format.
  58
  59 * Added --no-omagic to undo the effects of the -N option.
  60
  61 * Support for Texas Instruments TMS320C4x and TMS320C3x series of
  62   DSP's contributed by Michael Hayes and Svein E. Seldal.
  63
  64 * Added --with-lib-path configure switch to specify default value for
  65   LIB_PATH.
  66
  67 * ARM port to QNX operating system added by Graeme Peterson.
  68
  69 * IP2K support added by Denis Chertykov.
  70
  71 Changes in 2.13:
  72
  73 * Support for the Fujitsu FRV architecture added by Red Hat. Models for FR400
  74   and FR500 included.
  75
  76 Changes in version 2.13:
  77
  78 * DEC VAX ELF support, by Matt Thomas.
  79
  80 Changes in version 2.12:
  81
  82 * Support for Don Knuth's MMIX, by Hans-Peter Nilsson.
  83
  84 * Support for the OpenRISC 32-bit embedded processor by OpenCores.
  85
  86 * Support for -z nocopyreloc in the x86 ELF linker, which disables
  87   production of copy relocs.  Warning: using this option may result in
  88   non-sharable applications.
  89
  90 * Support for -z combreloc in the ELF linker, which puts dynamic
  91   relocations against the same symbol together, so that dynamic linker
  92   can use an one-entry symbol lookup cache.
  93
  94 * Support for ELF SHF_MERGE section merging, by Jakub Jelinek.
  95
  96 Changes in version 2.11:
  97
  98 * Support for AMD x86-64 architecture, by Jan Hubicka, SuSE Labs.
  99
 100 * Support added for eliminating duplicate DWARF2 debug information by
 101   having the compiler generate the information in sections called
 102   .gnu.linkonce.wi.XXXX where XXXX is a checksum for the contents.  The
 103   linker then merges these sections together into the normal .debug_info
 104   section.
 105
 106 * The native ELF linker now searches the directories in DT_RUNPATH or
 107   DT_RPATH of a shared library for shared libraries needed by it.
 108
 109 * TI C54x support, by Timothy Wall.
 110
 111 * Added command line switch --section-start to set the start address of any
 112   specified section.
 113
 114 * Added ability to emit full relocation information in linked executables,
 115   enabled by --emit-relocs.  Some post-linkage optimization tools need
 116   this information in order to be able to correctly identify and perform
 117   symbol relative addressing in the event of changes in section contents
 118   (instructions being added or deleted, extending data sections, etc.)
 119
 120 * Support for i860, by Jason Eckhardt (preliminary, alpha quality).
 121
 122 * Support for CRIS (Axis Communications ETRAX series).
 123
 124 * Support for PDP-11 and 2.11BSD a.out format, by Lars Brinkhoff.
 125
 126 Changes in version 2.10:
 127
 128 * Added AT> to the linker script language to allow load-time allocation of
 129   sections into regions.
 130
 131 * Added garbage collection of unused sections, enabled by --gc-sections.
 132   It does require a bit of backend support; currently implemented are
 133   arm-elf, avr-elf, d10v-elf, fr30-elf, i386-elf, m32r-elf, m68k-elf,
 134   mcore-elf, mips-elf, mn10300-elf, ppc-elf, sh-elf, sparc-elf, and v850-elf.
 135   Others will ignore the option.
 136
 137 * Added SORT to the linker script language to permit sorting sections by file
 138   name or section name.
 139
 140 * Added EXTERN to the linker script language as an equivalent to the -u
 141   command-line option.
 142
 143 * Added ASSERT to the linker script language.
 144
 145 * Added EXCLUDE_FILE to the linker script language for further control over
 146   wildcard file names.
 147
 148 * Added -O option to optimize linker output (as of this writing, this only
 149   affects ELF shared library generation).
 150
 151 * The -e option now accepts a number as well as a symbol name.
 152
 153 * Added --no-undefined option to disallow undefined symbols when creating a
 154   shared library.
 155
 156 * The linker now issues a warning, not an error, for an undefined symbol when
 157   using -Bsymbolic; use the new --no-undefined option to get the old
 158   behaviour.
 159
 160 * Added --demangle and --no-demangle options.
 161
 162 Changes in version 2.9:
 163
 164 * Added SQUAD to the linker script language.
 165
 166 * New option --no-warn-mismatch.
 167
 168 * The MEMORY command now parses the attributes to determine where sections that
 169   are not placed in a specific memory region are placed.
 170
 171 Changes in version 2.8:
 172
 173 * Linker scripts may now contain shell wildcard characters for file and section
 174   names.
 175
 176 * The linker now supports symbol versions in ELF.
 177
 178 * The NOCROSSREFS command was added to the linker script language.
 179
 180 * The LOADADDR expression was added to the linker script language.
 181
 182 * MAX and MIN functions were added to the linker script language.
 183
 184 * The OVERLAY construct was added to the linker script language.
 185
 186 * New option --warn-section-align to warn when the address of an output section
 187   changes due to alignment of an input section.
 188
 189 * New options --filter/-F and --auxiliary/-f.
 190
 191 Changes in version 2.7:
 192
 193 * New option --cref to print out a cross reference table.
 194
 195 * New option --wrap SYMBOL.
 196
 197 * New option --no-whole-archive, to turn off the effect of --whole-archive.
 198
 199 * Input sections assigned to the output section /DISCARD/ in the linker script
 200   are not included in the output file.
 201
 202 * The SunOS and ELF linkers now merge stabs debugging information which uses
 203   the N_BINCL and N_EINCL stab types.  This reduces the amount of debugging
 204   information generated.
 205
 206 Changes in version 2.6:
 207
 208 * When an ELF section name is representable as a C identifier (this is not true
 209 of most ELF section names), the linker will automatically define symbols
 210 __start_SECNAME and __stop_SECNAME, where SECNAME is the section name, at the
 211 beginning and the end of the section.  This is used by glibc.
 212
 213 * When an ELF section named .gnu.warning is encountered in an input file, the
 214 contents of the section are displayed as an error message, and the section is
 215 not copied into the output file.  This is used by glibc.
 216
 217 * When an ELF section named .gnu.warning.SYMBOL is encountered in an input
 218 file, and the symbol SYMBOL is referenced by some object file, the contents of
 219 the section are displayed as an error message.  The section is not copied into
 220 the output file, unless doing a relocatable or shared link.  This is used by
 221 glibc.
 222
 223 * New options -split-by-reloc and -split-by-file.
 224
 225 * The linker now supports linking PIC compiled code on SPARC SunOS.  It can
 226 also create SPARC SunOS shared libraries, and, like the native SunOS linker,
 227 will do so whenever there is an undefined symbol in the link and neither the -e
 228 nor the -r option was used.
 229
 230 * The -rpath option may be used on SunOS to set the list of directories to be
 231 searched at run time.  This overrides the default of building the list from the
 232 -L options.
 233
 234 * The COFF linker now combines debugging information for structs, unions, and
 235 enums, so that even if the same type is defined in multiple input files it will
 236 only be defined once in the output file.  The --traditional-format switch will
 237 prevent this optimization.
 238
 239 Changes in version 2.5:
 240
 241 * The linker now supports linking against SunOS shared libraries.  It still can
 242 not link SunOS PIC (Position Independent Code) files, so it can not be used to
 243 generate shared libraries.
 244
 245 * The linker now supports linking against ELF shared libraries for the i386
 246 (UnixWare) and SPARC (Solaris).  It can also link ELF PIC files, and can be
 247 used to generate shared libraries.  Shared library generation is not well
 248 tested; please report any problems encountered.  The linker is now enabled for
 249 Solaris again.
 250
 251 * Eric Youngdale has contributed Linux support code, including linking against
 252 Linux a.out shared libraries.  The linker produces Linux QMAGIC binaries.
 253
 254 * The ELF backend has been converted to the new linker code.  To use the new
 255 ELF linker, each particular target requires a relocation function.  So far,
 256 this function has been written for i386 (UnixWare), SPARC (Solaris) MIPS (Irix
 257 5), and HPPA ELF targets.
 258
 259 * The -( (--start-group) and -) (--end-group) options have been added to
 260 support searching a group of archives as though they were a single archive.
 261 This can also be used in a linker script, as GROUP ( files ).
 262
 263 * When a file is named on the command line, and the linker does not recognize
 264 it as an object file, the linker will now treat the file as a linker script
 265 file.  A linker script named in this way augments, but does not replace, the
 266 default linker script.
 267
 268 * The -warn-once option was added.  It causes the linker to only warn once per
 269 undefined symbol, rather than once per reference.
 270
 271 * The COFF backend has been converted to the new linker code.  As with ELF, to
 272 use the new linker, each particular target requires a relocation function.  So
 273 far, this function has been written for the i386, m68k, a29k and SH targets.
 274
 275 * The -V flag was made a synonym for -v, for SVR4 compatibility.  The old -V
 276 behaviour is available via --verbose.
 277
 278 Changes in version 2.4:
 279
 280 * New linker code, by Steve Chamberlain and Ian Taylor.  For a.out and ecoff
 281   formats (so far), this should result in considerable savings in time
 282   and memory used while linking; slightly poorer performance than
 283   before for formats not converted yet.
 284
 285 * Command-line parsing is no longer done with flex.  This means
 286   oddball characters in filenames won't get treated as argument
 287   separators.
 288
 289 * HP-PA ELF support, by Jeff Law.  (No SOM support yet.)
 290
 291 * Mach i386 support, by David Mackenzie.
 292
 293 * Irix 4 shared libraries are now supported (Irix 5 uses ELF, and ELF shared
 294   libraries are not yet supported).
 295
 296 * COFF shared libraries (as on SCO) should work as well.
 297
 298 * The linker is disabled for Solaris.  (Actually, it was in 2.3 also, I just
 299   forgot to note it.)  Some of their C library routines don't work when
 300   statically linked, and the GNU linker doesn't support dynamic linking yet.
 301
 302 Changes in version 2.3:
 303
 304 * Weak symbols are now supported.
 305
 306 * ELF support has been added.  The linker has been bootstrapped on
 307   UnixWare and Solaris.
 308
 309 * Alpha OSF/1 support has been added (non dynamic linking only).
 310
 311 Changes in version 2.2:
 312
 313 * The `bfd' library has been updated to reduce a.out-format string
 314   table size.  The effect of this is that files linked from many input
 315   files with duplicate symbols (`-g' debugging records, or identical
 316   static symbols) should be much smaller.
 317
 318 Changes in version 2.1:
 319
 320 * The ld -ySYMBOL flag (to trace references to SYMBOL) is now implemented.
 321
 322 * There is now support for writing ECOFF files, so ld and the
 323   other utilities should work on Risc/Ultrix and Irix.
 324
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